Just google dumbbell shrugs and find some videos to get an idea. I could send you videos from online as well - but there is no point, you'll be able to find plenty on your own.

You told me to do jumping squats and underwater exercises..but what I meant now was how should plyos be set up? are they supposed to be done in timed intervals, or set rep schemes, with weight, etc?

it all depends...I don't believe in doing plyometrics as anything more than a form of supplemental exercise because of their fast-twitch explosive nature. However, the best way for integrating them into a daily routine is to stick like muscle groups with like muscle groups and do your plyometrics either before or after regular training (with explosive form). Now as far as the scheme goes...I would recommend doing failure sets until exhaustion. Then take a short break of no longer than 30 seconds, and go again until failure. This will help with your stamina. I would repeat the failure sets for at least 5 cycles.

haha thats the type of thing I was looking for...thanks

How long does the stimulus for growth last? Is there a timed window after u workout that growth occurs?

after a workout there is approximately a 20-40 minute window that your body responds to immediate protein and glycogen synthesis. After that time, the body starts going catabolic.

when do I stop growing as a result of hypertrophy

growth isn't as cut and dry as that.

for growth to occur, it requires many things including the tearing of muscle fibers, proper amino acid intake, adequate glycogen, an anabolic environment, sufficient sleep, etc. There is no time when you simply "stop" or "start" growing. Its a constant ongoing thing - and once treated as such, can be utilized and optimized for your advantage.

Well damn hack squats hurt my knees real bad too, so i had to stick to lunges... will i be able to gain alot of mass(that's my goal) with this on leg day? :

4x8-12 lunges
4x8-12 leg press
4x4-8 laying hamstring curls
4x8-12 leg extensions

and on top of that what should my foot placement be for the leg press? should i just put my feet right in the middle normal width, or wide, or at the top or bottom, etc...

what will build as much leg mass as possible. given your circumstances.

As for the leg press, keep your feet approx shoulders width apart